Telephone system



Feb. 20, 1951 c. E. LOMAX ETAL 2,542,283

TELEPHONE SYSTEM Filed March 5, 1947 14 Sheets-Sheet 1 DIVISION *1 I2" I! @g 9L8 No 1 Choice Finder 300A 1 Selector 400A 2 Selector 600A us 502 1 us es L0 as us iTrunk T5|O DisTribumr IOOOA 203 203 DIVISION 2 q 2 ljnder ,0 i'Selecior 400B 2 Selecior 600B 20| US gs INVENTORS BY CLARENCE E IZOMAX HANS SENGEBUSCH ATTORNEYS Feb. 20, 1951 c. E. LOMAX ETAL 2,542,283

TELEPHONE SYSTEM Filedhlarch 5, 1947 14 Sheets-Sheet 2 FIG. 2

a z' -choice 2'Se|ector 600C Connecjor 800A us (as 12m T725 i E L Connector 800B I l L INVENTORS BY CLARENCE E. LOMAX HANS SENGEBUSCH ATTORNEYS Feb. 20, 1951 c. E. LOMAX ETAL 2,542,283

TELEPHONE sysmx Filed March 5, 1947 14 Sheets-Sheet 3 E B3 I 7 3 3MP 9%: 520% E:

INVENTORS CLARENCE E. LOMAX HANS SENGEBUSCH momma 20E :2; Sn

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ATTORNEYS C. E. LOMAX ET AL TELEPHONE SYSTEM 14 Sheets-Sheet 4 Filed March 5, 1947 32w 25 SE mTQJ N3 3 SE $3 TEE 2v 5% i 9% e 92 WIRE; :ww n 4923 E? 53% 86 @Q N; X J @w m? 08 2% Em E H Y M C E S 0 5 N R L U R O B O TEE T N G T E E N A VCE N N S I E R 5 I A N L A C H Y B Feb. 20, 1951 Filed March 5, 1947 2 Selector 600A Unit Switch 703 c. E. LOMAX ETAL TELEPHONE SYSTEM l4 Sheets-Sheet 7 Group Switch 702 INVENTORS CLARENCE E. LOMAX Y HAN S SENGEBUSGH! ATTORN EYE Feb. 20, 1951 c. E. LOMAX arm. 2,542,233

TELEPHONE SYSTEM Filed March 5, 1947 14 Sheets-Sheet 12 FIG. l2 FIG. l3

INSULATION AIAINSULATIONJ gs i GBlOl "LLl2l IN VEN TOR.

CLARENCE E. LOMAX HANS SENGEBUSCH ATTORNEYS Feb 20, 1951 c. E. LOMAX ETAL 2,542,283

TELEPHONE svswm mm March 5, 1947 '14 sheets-sheet 14 FIG. I? 5135 Group Swifch I02 INVENTOR. CLARENCE E. LOMAX m HANS SENGEBUSCH ATTORNEYS Patented Feb. 20, 1951 TELEPHONE SYSTEM Clarence E. Lomax,'0hicago, and Hans Sengebusch, Villa Park, Ill., assignors to Automatic Electric Laboratories, Inc., Chicago, 111., a. corporation of Delaware Application March 5, 1947, Serial No. 732,417

13 Claims. 1

The present invention relates to telephone systems and more particularly to improved switching apparatus for setting up telephone connections.

It is an object of the present invention to provide an automatic telephone system including finders, selectors and connectors, each comprising improved switching apparatus of economical construction and arrangement.

Another object of the invention is to provide switching apparatus of the character mentioned comprising an improved group switch and an improved unit switch.

Another object of the invention is to provide a group switch of the character mentioned of improved mechanical construction and arrangement.

A further object of the invention is to provide in a selector improved switching apparatus of the type noted, wherein the group switch is arranged to respond directly to a digit transmitted over the associated trunk in order to perform a group selection and the unit switch is arranged to carry out a trunk-hunting operation in order to perform a unit selection.

A further object of the invention is to provide in a connector improved switching apparatus of the type noted, wherein the group switch and the unit switch are arranged to respond directly and successively to two digits transmitted over the associated trunk in order to perform successively group and unit selections.

A further object of the invention is to provide in a finder improved switching apparatus of the type noted, wherein the group switch and the unit switch are arranged to be operated respectively directly in accordance with the group and the unit positions of a calling subscriber line in order to perform the corresponding group and unit selections.

A still further object of the invention is to provide in a telephone system an improved overflow trunking arrangement utilizing selectors incorporating switching apparatus of the character described.

Further features of the invention pertain to the particular arrangement of the circuit elements of the system, whereby the above outlined and additional operating features thereof are attained.

The invention, both as to organization and method of operation, together with further objects and changes thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawings which Figures 1 and 2, taken together, illustrate diagrammatically a telephone system having incorporated therein the features of the present invention; Figs. 3 to 10, inclusive, taken together, illustrate the details of a portion of the telephone system illustrated in Figs. 1 and 2 and embodying the features of the present invention; and Figs. 11 to 16, inclusive, and 19 illustrate the mechanical construction and arrangement of a group switch incorporated in finders, selectors and connectors employed in the telephone system; and Figs. 17 and 18 illustrate the mechanical construction and arrangement of an auxiliary switch incorporated in the group switches employed in the finders utilized in the telephone system.

More particularly, in order to form a unified diagram, Figs. 1 and 2 should be arranged from left to right in side-by-side relation. Also, in order to form a unified diagram, Figs. 3 to 9, inclusive, should be arranged from left to right in endto-end relation; and Fig. 10 should be arranged sidewise and disposed below Fig. 3.

More particularly, Fig. 11 is a front elevational view, partly broken away, of the group switch mentioned; Fig. 12 is a side elevational. view, partly broken away, of the group switch shown in Fig. 11, together with a portion of the associated support; Fig. 13 is an enlarged, framentary plan view of one of the operating mechanisms for one of the groups of contact sets incorporated in the group switch shown in Figs. 11 and 12; Fig. 14 is an enlarged, side elevational view of the operating mechanism shown in Fig. 13; Fig. 15 is an enlarged, fragmentary front elevational view of the operating mechanism shown in Figs. 13 and 14; Fig. 16 is a plan view, partly broken away, of the group switch shown in Figs. 11 and 12; Fig. 17 is an enlarged plan view of the auxiliaryswitch incorporated in the group switch employed in the finder mentioned; Fig. 18 is a side elevational view, partly in section taken along the line l8-l8 in Fig. 1'7, of the auxiliary switch; and Fig. 19 is a sectional view, taken along the line l9-l 9 in Fig. 11, of a portion of the group switch shown in Figs. 11, 12 and 16, and illustrating the details of a rotary ofi-normal contact spring assembly incorporated therein.

Referring now, more particularly, to Figs. 1 and 2 of the drawings, there is illustrated an automatic telephone system comprising an exchange terminating several thousand subscriber lines arranged in two divisions, #l and #2. Division #l includes the subscriber lines I2 and 3H respectively extending to the subscriber substations A and B; while division #2 includes the subscriber lines 2!, 202 and 203 respectively extending to the subscriber substantions X, Y and Z. Each subscriber line is provided with a line circuit individual thereto, the line circuits 90E, 30l, 2i I, H2 and H3 being respectively individual to the subscriber lines |2| I, 3|2, 2M, 202 and 203. Also, the system comprises switching apparatus disposed in the two divisions and including finders, first selectors, second selectors and connectors.

The subscriber lines l2 and 3|2 are disposed in the twelfth IOU-line group in dvision #I and are provided with a group of finders, including the finder 300A, and a group of connectors, including the connector 800A. Also, division #I includes a plurality of groups of first selectors; one of the groups, including the first selector 400A, being associated with the group of finders, including the finder 330A. Further, division #I includes a plurality of groups of second selectors one of the groups including the second selector 686A; as well as the second selector 5000. In the arrangement the finder 308A has access to the twelfth 100-line group, including the subscriber lines I21! and 3l2, and is individually associated with the first selector 400A. Also, the first selector 400A has access to the second selector 600A as well as to the second selector 6000. Finally, both the second selector GS BA and the second selector 6000 have access to the connector 800A; while the connector 399A has access to the twelfth IOU-line group, including the subscriber lines 12H and 3l2. Further, each 100-line group is provided with a distributor individual thereto that is associated with the corresponding group of finders; the distributor IOODA being individual to the twelfth IOQ-line group, including the subscriber lines l2ll and M2, and being associated with the group of finders, including the finder 300A.

Similarly, the subscriber lines 2M, 202 and 203 are disposed in a given 100-line group in division #2 and are provided with a group of finders, including the finder 3003, and a group of connectors, including the connector 800B. Also, division #2 includes a plurality of groups of first selectors; one of the groups, including the first selector 4903, being associated with the group of finders, including the finder 3130B. Further, division #2 includes a plurality of groups of second selectors, one of the groupsincluding the second selector 6003; as well as the second selector 660C; whereby the second selector 6090 is common to divisions #l and #2. In the arrangement the finder 3003 has access to the IOU-line group, including the subscriber lines 202 and 203, and is individually associated with the first selector 4003. Also, the first selector 408B has access to the second selector 6003 as well as to the second selector 690C. Finally, both the second selector 600B and the second selector 5000 have access to the connector 800B; while the connector 3003 has access to the 100-line group, including the subscriber lines 20!, 202 and 263. Further, each of the lOO-line groups is provided with a distributor individual thereto that is associated with the correspond ing group of finders; the distributor lflt iB being individual to the 100-line group, including the subscriber lines 20!, 202 and 203, and being associated with the group of finders, including the finder 3603.

In view of the foregoing description of the arrangement of th switching apparatus in divisions #l and #2, it will be understood that the first selector 400A has first choice access to the group of second selectors, including the second selector 600A, and second choice or overflow access to the second selector 600C. Likewise, the first selector 400B has first choice access to the group of second selectors, including the second selector 60GB, and second choice or overflow access to the second selector 600C. Accordingly, in the extension of a connection from a subscriber substation in division #I, such, for ex ample, as the subscriber substation B, to ane other subscriber substation in division #I, such, for example, as the subscriber substation A, the distributor HHIOA may allot the finder 300A to the calling subscriber substation B. Then the first selector 400A is operated to select an idle one of th second selectors in the group, including the second selector 680A, or to select the second selLctor 600C in the dual events that all of the second selectors in the group, including the second selector 608A, are busy and the sec- .ond selector 6090 is idle. Thereafter, either the second selector in the group, including the second selector 580A, or the second selector 600C may be controlled to select an idle connector in the group, including the connector 800A; whereupon the connector mentioned may be controlled to seize the subscriber line l2ll extending to the called subscriber substation A.

Similarly, in the extension of a connection from a subscriber substation in division #2, such, for example, as the subscriber substation -X, to a subscriber substation in division #I, such, for example, as the subscriber substation A, the distributor 1000B may allot the finder 300B to the calling subscriber substation X. Then the first selector 40013 is operated to select an idle one of the second selectors in the group, including the second selector 6903, or to select the second selector 609C in the dual events that all of the second selectors in the group, including the second selector 660B, are busy and the second selector 6080 is idle. Thereafter, either the second selector in the group, including the second selector 600B, or the second selector 6000 may be controlled to select an idle connector in the group, including the connector 890A; whereupon the connector mentioned may be controlled to seize the subscriber line 12H extending to the called subscriber substation A.

Preferably, ac line circuits 3M, 90!, etc. are identical; the line circuit 3! comprising, as shown in Fig. 3, a line relay R3|5 and a cutoff relay R3I0.

Preferably, each of the finders is identical to the finder 300A which comprises, as shown in Fig. 3, a group switch 302 and a unit switch 303,

as well as a relay group including'a cut-through relay R350, a start relay R360 and a stop relay R310.

The group switch 3B2 is of the construction and arrangement illustrated in Figs. 11, etc. and described more fully hereinafter. Specifically, the group switch 392 comprises one hundred group contact sets GCSH to GC3U0, inclusive, arranged in ten groups of ten group contact sets each; and ten group members or bars GB30| to GB300, inclusive, respectively associated with the ten groups of group contact sets. Also, the group switch 302 comprises an operating element 320 mounted for both rotary movement and longitudinal sliding movement and having no rotary home position, but a longitudinal home position;

and carrying ten operating lugs or fingers F32l to F320, inclusive. The operating fingers F32l, etc., are disposed in longitudinal and angular spaced apart relation, whereby the fingers F32!, F322, etc. are disposed in a helical path about the operating element 320. The ten operating fingers F32l, etc. are respectively associated with the ten group bars Gl330l etc. through the intermediary of a group of ten pivotally mounted bell cranks L32! to L320, inclusive, respectively positioned therebetween. Further the group switch 302 is provided with a rotary magnet M329 having an associated pawl and ratchet mechanism 321 operatively connected to the operating element 320; as well as a lift magnet M330 having an associated armature 332 operatively connected to the operating element 320.

The unit switch 303 comprises ten unit contact sets U030! to UC300, inclusive, terminating a group of ten busses commonly associated with the ten groups of group contact sets in the group switch 302. Also, the unit switch 303 comprises an operating element 340 mounted for rotation and carrying ten operating lugs or fingers F3 to F340, inclusive. The operating fingers F3, etc. are disposed in longitudinal and angular spaced apart relation, whereby the fingers F3, F342, etc. are disposed in a helical path about the operating element 340. The ten operating fingers F3, etc. are respectively associated with the ten unit contact sets UC30I, etc. Further, the unit switch 303 is provided with a rotary magnet M349 having an associated pawl and ratchet mechanism 341 operatively connected to the operating element 340. The operating element 340 has no home position and is adapted to occupy any one of its ten rotary stepped positions, thereby to operate the associated one of the unit contact sets UC30I, etc.

Finally, an auxiliary switch S335, of the construction of that shown in Figs. 1'7 and 18 and described hereinafter, is operatively connected to the group switch 302. Specifically, the auxiliary switch S335 essentially comprises a wiper 336 mounted upon the operating element 320 of the group switch 302 and capable of rotation therewith; the wiper 336 being provided with an associated contact bank terminating ten mark con duciors C336, etc. respectively extending to the ten subgroups of ten lines each in the twelfth IOU-line group, including the subscriber line 3!2 extending to the subscriber substation B.

Preferably, each of the first selectors is identical to the first selector 400A which comprises, as shown in Figs. 4 and 5, a group switch 502 and a unit switch 503, as well as a relay group including a switch relay R4l0, a line relay R420, 8. hold relay R430, a transfer relay R440, a test relay R450 and a busy relay R460.

The group switch 502 is of the construction and arrangement illustrated in Figs. 11, ec. and described more fully hereinafter. Specifically, the group switch 502 comprises one hundred group contact sets G05! I to GC500, inclusive, arranged in ten groups of ten group contact sets each; and ten group members or bars GB50I' to GB500, inclusive, respectively associated with the ten groups of group contact sets. Also, the group switch 502 comprises an operating element 520 mounted for both rotary movement and longitudinal sliding movement and having rotary and longitudinal home positions; and carrying ten operating lugs or finger F52! to F520, inclusive. The operating fingers F52! etc. are disposed in longitudinal and angular spaced apart relation, whereby the fingers F521, F522, etc. are disposed in a helical path about the operating element 520. The ten operatin fingers F52l, etc. are respectively associated with the ten group bars GB50I, etc. through the intermediary of a group of pivotally mounted bell cranks L52! to L520, inclusive, respectively positioned therebetween. Further, the group switch 502 is provided with a rotary magnet M529 having an associated pawl and ratchet mechanism 521 operatively connected to the operating element 520; as well as a lift magnet M530 havin an associated armature 532 operatively connected to the operating element 520.

The unit switch 503 comprises ten unit contact sets U050! to UC500, inclusive, terminating a group of ten busses commonly associated with the ten groups of group contact sets in the group switch 502. Also, the unit switch 503 comprises an operating element 540 mounted for rotation and carrying eleven operating fingers or lugs F5 to F540, inclusive, andF540'. The operating fingers F54 I, etc. are disposed in longitudinal and angular spaced apart relation, whereby the ten fingers F54! to F540, inclusive, and the eleventh finger F540 are disposed in a helical path about the operating element 540. The ten operating fingers F5 to F540, inclusive, are respectively associated with the ten unit contact sets UC50! to UC500, inclusive; while the eleventh finger F540 is associated with a set of switch springs US5! I utilized for a purpose more fully explained hereinafter. Further, the unitswitch 503 is provided with a rotary magnet M549 having an associated pawl and ratchet mechanism 541 operatively connected to the operating element 540. The operating element 540 has a home position wherein it occupies its first position, thereby to operate the associated first unit contact set UC50I.

Also associated with the grou switch 502 are the sets of switch springs G84, GS454 and GS536 which are actuated in response to rotation of the operating element 520 in the rotary direction away from its home position. Similarly, associated with the unit switch 503 are the sets of switch springs US438 and US550 which are actuated in response to rotation of the operating element 540 in the rotary direction away from its home position.

Preferably, each of the second selectors is identical to the second selector 600A which comprises, as shown in Figs. 6 and '1, a group switch 102 and a unit switch 103, as well as a relay group including a switch relay R610, a line relay R620, a hold relay R630, a transfer relay R640, a test relay R650, a busy relay R660 and a control relay R610.

The group switch 102 is of the construction and arrangement illustrated in Figs. 11, etc. and described more fully hereinafter. Specifically, the group switch 102 comprises one hundred group contact sets GCll l to GC100, inclusive, arranged in ten groups of ten group contact sets each: and ten group members or bars GB10! to GB100, inclusive, respectively associated with the ten groups of group contact sets. Also, the group switch 102 comprises an operating element mounted for both rotary movement and longitudinal sliding movement and having rotary and longitudinal home positions; and carrying ten operating lugs or fingers F12! to F120, inclusive. The operating fingers F12l, etc. are disposed in longitudinal and angular spaced apart relation, whereby the fingers F12!, F122, etc. are disposed in a helical path about the operating element 120. The ten operating fingers F12I, etc., are respec- 7 tively associated with the ten group bars GB10I, etc., through the intermediary of a group of pivotally mounted bell cranks L12I to L120, 111- clusive, respectively positioned therebetween. Further, the group switch 102 is provided with a rotary magnet M129 having an associated pawl and ratchet mechanism 121 operatively connected to the operating element 120; as well as a lift magnet M130 having an associated armature I32 operatively connected to the operating element 120.

The unit switch 103 comprises ten unit contact sets UC10I to UC100, inclusive, terminating a group of ten busses commonly associated with the ten groups of group contact sets in the group switch 102. Also, the unit switch 103 comprises an operating element 140 mounted for rotation and carrying ten operating fingers or lugs F14I to F140, inclusive. The operating fingers F14I, etc. are disposed in longitudinal and angularly spaced apart relation; whereby the fingers F14I, etc. are disposed in a helical path about the operating element 140. The ten operating fingers F14I to F140, inclusive, are respectively associated with the ten unit contact sets UC10I to UC100, inclusive. Further, the unit switch 103 is provided with a rotary magnet M149 having an associated pawl and ratchet mechanism 141 operatively connected to the operating element 140. The operating element 140 has no home position and is adapted to occupy any one of its ten rotary stepped positions, thereby to operate the associated one of the unit contact sets UC10I, etc.

Also, associated with the group switch 102 are the sets of switch springs GS64I, (38654 and GS136, which are actuated in response to rotation of the operating element 120 in the rotary direction away from its home position.

Preferably, each of the connectors is identical to the connector 000A, which comprises, as shown in Figs. 8 and 9, a group switch 902 and a unit switch 903, as well as a relay group including a line relay R8I0, a hold relay R820, a control relay R830, two transfer relays R840 and R850, a busy relay R860, an answer relay R810, a ring cutoff relay R880 and a switch relay R890.

The group switch 902 is of the construction and arrangement illustrated in Figs. 11, etc. and described more fully hereinafter. Specifically, the group switch 902 comprises one hundred grou contact sets GC9II to GC900, inclusive, arranged in ten groups of ten group contact sets each; and ten group members or bars GB90I to GB900, inclusive, respectively associated with the ten groups of group contact sets. Also, the group switch 902 comprises an operating element 920 mounted for both rotary movement and longitudinal sliding movement and having rotary and longitudinal home positions; and carrying ten operating lugs or fingers F92I to F920, inclusive. The operating fingers F92I, etc. are disposed in longitudinal and angular spaced apart relation, whereby the fingers F92I, F922, etc. are disposed in a helical path about the operating element 920. The ten operating fingers F92I, etc. are respectively associated with the ten group bars GB90I, etc. through the intermediary of a group of pivotally mounted bell cranks L92I to L920, inclusive, respectively positioned therebetween. Further, the group switch 902 is provided with a rotary magnet M929 having an associated pawl and ratchet mechanism 921 operatively connected to the operating element 920; as well as a lift magnet M930 having an associated armature 932 operatively connected to the operating element 920.

The unit switch 903 comprises ten unit contact sets UCI to UC900, inclusive, terminating a group of ten busses commonly associated with the ten groups of group contact sets in the group switch 902. Also, the unit switch 903 comprises an operating element 940 mounted for rotation and carrying ten operating fingers or lugs F94I to F940, inclusive. The operating fingers F94l, etc., are disposed in longitudinal and angularlv spaced apart relation whereby the fingers F94I, etc., are disposed in a helical path about the operating element 940. The ten operating fingers F94I to F940, inclusive, are respectively associated with the ten unit contact sets UC90I to UC900. inclusive. Further, the unit switch 903 is provided with a. rotary magnet M949 having an associated pawl and ratchet mechanism 941 operatively connected to the operating element 940. The operating element 940 has a home position wherein it occupies its tenth position, thereby to operate the associated tenth unit contact sets UC900.

Also, associated with the group switch 902 are the sets of switch springs GS80I, GS804, GS952 and GS953 which are actuated in response to rotation of the operating element 920 in the rotary direction away from its home position. Similarly associated with the unit switch 903 are the sets of switch springs US002, US$03 and US95I which are actuated in response to rotation of the operating element 943 in the rotary direction away from its home position.

Preferably, each of the distributors is identical to the distributor I000A, which comprises, as shown in Fig. 10, a selecting switch IO0I, a timer I092 and a relay group including a start relay RIOI0, a restore relay RI020, a start slave relay RI030, a test relay RI050, two timing relays RI060 and RI080, a step relay RI010 and an interrupter relay RI090. The selecting switch IO0I comprises ten contact sets SIO0I to SIO'00, inclusive, terminating groups of control conductors respectively extending to the finders 300A, etc. in the associated group serving the twelfth IOU-line group in division #I. Also, the selecting switch IO0I comprises an operating element I040 mounted for rotation and carrying ten operating fingers or lugs FI04I to FI040, inclusive. The operating fingers FI04I, etc. are disposed in longitudinal and angularly spaced apart relation; whereby the fingers FI04I, etc. are disposed in a helical path about the operating element I040. The ten operating fingers FI04I to FI040, inclusive, are respectively associated with the contact sets SIO0I to SI000, inclusive. Further, the selecting switch IO0I is provided with a rotary magnet MI049 having an associated pawl and ratchet mechanism I041 operatively connected to the operating element I040. The operating element I040 has no home position and is adapted to occupy any one of its ten rotary stepped positions, thereby to operate the associated one of the contact sets SI00-I, etc.

As previously noted, each of the finders 300A etc., first selectors 400A etc., second selectors 600A etc. and connectors 803A etc. comprises a group switch substantially identical to that shown in Fig. 11 etc. Referring now more particularly to Figs. 11 to 16, inclusive, and 19, the group switch I02 there illustrated comprises a frame 220 supporting a plurality of laterally extending and longitudinally spaced apart shelves or plates 22I and two longitudinally extending side plates 222 and 223. The uppermost shelf 22l carries a laterally extending and iorwardly projecting insulating strip 224; each of the other shelves 22I carries a laterally extending and forwardly projecting insulating strip 225; and the lower wall of the frame 220 carries a laterally extending insulating block 226. A bare bus bank 221 is supported by the insulating strips 224 and 225; the bus bank 221 comprising ten individual busses, each including three individual conductor strips. Specifically, the upper ends of the conductor strips forming the bus bank 221 are imbedded in the insulating strip 224 while the longitudinally spaced apart intermediate portions of the conductor strips are supported in aligned slots formed in the insulating strips 225. The insulating block 220 carries a plurality of laterally spaced apart and forwardly projecting terminals 228 imbedded therein and engaging the lower ends of the conductor strips forming the bus bank 221 and being soldered thereto; whereby the ten busses are accessible from the rear of the frame 220 by way of the rear ends of the terminals 228.

Also, the frame 22!] supports ten laterally extending group bars GBluI to (3310:], inclusive, each mounted for lateral movement by an arrangement including an associated bell crank disposed adjacent to the side plate 223 and an associated link disposed ad acent to the side plate 222. For example, the first group bar GBIu-l is pivotally mounted adjacent the right-hand end thereof upon the associated bell crank LI2I and adjacent to the left-hand end thereof upon the associated link 229. Specifically, the bell crank LIZI is pivotally mounted both to the right-hand end of the first group bar GBIUI and to a downwardly extending tab 230 formed integrally with the associated shelf 22I by an arrangement including a screw 23I; and the link 22%! is pivotally mounted both to the lefthand end of the first group bar GBI Ill and to a downwardly extending tab 232 formed integrally with the associated shelf 22I by an arrangement including a screw 233. More particularly, the ten group bars GBIIJI to GBIUU, inclusive, are provided with the individually associated bell cranks Ll2l to 'LI20, inclusive, each mounted adjacent to the side plate 223, in the manner previously explained.

Further, the frame 220 carries ten laterally extending insulating blocks 234 supported upon the top surfaces of the shelves 22l disposed below the uppermost shelf 22I. This construction is best illustrated in Figs. 14 and wherein the insulating block 234 is illustrated as being supported adjacent to the rear of and upon the top surface of the shell 222i upon which the first group bar GBIUI is mounted. As illustrated, the insulating block 234 carries a plurality of laterally spaced apart and forwardly projecting switch springs 235, the extreme forward end of each switch spring 235 being bifurcated to provide two arms 235 and 231, each carrying precious metal contacts 238. The forward ends of the arms 236 and 231 carried by each switch spring 235 project into intersecting relation with respect to an associated one of the conductor strips forming the bus bank 221 and are disposed to the right of the conductor strip mentioned, as illustrated in Fig. 11. More specifically, thirty of the switch springs 235 are provided and arranged in ten sets of three respectively corresponding to the ten busses included in the bus bank 221. The intermediate portions of the switch springs 235, disposed rearwardly of the arms 238 and 231 thereof, are supported by a strip of insulation 23!] carried by the associated group bar GBIUI; specifically, the switch springs 235 are disposed in a plurality of laterally spaced apart notches formed in the insulating strip 239. Finally, the rear ends 248 of the switch springs'235 constitute terminals accessible at the rear of the frame 220. In view of the above description it will be understoodthat when the first group bar GBIIJI is moved toward the left upon the associated bell crank LI2I and link 229, that the strip of insulation 239 carried thereby forces the ten sets of switch springs 235 toward the left, whereby the contacts 238 carried by the arms 233 and 23! thereof engage the associated conductor strips in the bus bank 221. Accordingly, when the first group bar GB I UI is operated the ten busses in the bus bank 221 are electrically connected to the ten sets of switch springs aisociated with the first group ear GBiBI. Considering the bus bank 221 and the ten groups of ten sets of switch springs 235 collectively, it will be appreciated that the arrangement constitutes the IOU-group contact sets GCI I I to GCI 00, inclusive; each group bar GBI OI etc. being individually associated with a group of ten of the group contact sets; and each bus in the bus bank 221 being associated with an inter secting group of ten of the group contact sets. For example, the first group bar GBIOI is associated with the group of ten group contact sets "GCI I I, GCI l2, etc., GCI I9 and'GCI 10; While the first bus in the bus bank 221 is associated with the intersecting group of ten group contact sets GCIII, GCI2I, etc., GCi9I and GCIOI. Accordingly, it will be understood that the ten group bars GBIOI, etc. are selectively operative, thereby to connect the individually associated ten sets of switch springs 235 to the ten busses in the bus bank 221.

Also, the group switch I 02 comprises a longitudinally extending operating element I20 mounted upon upper and lower brackets '2 II and 242, respectively, and capable of both rotary movement and longitudinal sliding movement and having rotary and longitudinal home positions. The operating element I20 carries ten operating lugs or fingers FI 2i to FI20, inclusive, disposed in longitudinal and angular spaced relation; whereby the fingers FIZI etc. are disposed in a helical path about the operating element I20. More particularly, the ten operating fingers Fi2I etc. are respectively associated with the ten bell cranks LI2I etc. and, consequently, with the respective group bars GBIDI, etc. More particularly, the operating element I20 may be selectively rotated, whereby the fingers FIZI, FI22 etc. are sequentially brought into alignment with the ends of the azsociated bell cranks LI2I, LI22, etc. and then sequentially moved out of alignment with the associated bell cranks; whereby in any given rotary position of the operating element I20 a given one of the fingers FIZ I, etc. is arranged in alignment with respect to the associated one of the bell cranks LIEI etc. At this time the operating element I20 may be slid longitudinally toward the top of the frame 22!], thereby to cause the finger Fl2I etc. to engage the associated selected bell crank LI2I, etc., whereby the engaged bell crank LI2I, etc. is rotated on its associated pivot 23I in the counterclockwise direction, as viewed in Fig. 11, thereby to move the associated group bar GBiOI, etc. toward the left. When the associated group bar GBIUI, etc. is thus operated, the ten sets of switch springs 235 individually associated therewith are operated into respective engagements with the ten busses in the bus bank 221. Subsequently, when the opetating element I is released it is returned longitudinally toward the bottom of the frame 220 by the action of gravity, whereby the operated bell crank LI2I, etc. is released in order to release the associated group bar GBIUI, etc. The operated group bar GBIOI, etc. is then returned to its normal position, by virtue of the resiliency of the ten sets of switch springs '235 associated therewith, in order to open the ten group contact sets individually associated therewith.

Further, the group switch I02 comprises a rotary magnet MI29 and a lift magnet MI30. As best shown in Figs. 11, 12 and 16, the rotary magnet MI29 comprises a heel piece 243 formed integrally with the upper bracket 24I, a core 244 carrying a winding 245, and an armature 246 pivotally mounted upon the heel piece 243. A pawl and ratchet mechanism I21 operatively eonnects the armature 246 to the operating element I20 and: comprises a ratchet wheel 241 rigidly secured to the operating element I20 adjacent to the upper end thereof, and a pawl 248 pivotally mounted on the upper end of the armature 246. The pawl 248 is normally biased toward the ratchet wheel 241 by an arrangement including a coil spring 249 extending between the pawl 248 and the armature 246. Also, the armature 246 carries a leaf spring 250, the outer end of which engages the upper bracket 24 I, thereby to bias the armature 246 in the counterclockwise direction, as viewed in Fig. 16, away from the operating element I20. It will be understood that each time the winding 245 is energized the core 244 attracts the armature 246, causing it to be pivoted in the clockwise direction, as viewed in Fig. 16, against the bias of the leaf spring 250 engaging the upper bracket 24I; whereby the pawl 248 engaging a tooth on the ratchet wheel 241 rotates the ratchet wheel 241 one step in the clockwise direction, thereby to effect rotation of the operating element I 20 one step in the clockwise direction. Subsequently, when the winding 245 is deenergized, th core 244 releases the armatur 246, whereb the leaf spring 250 returns the armature 246 to its normal position causing the pawl 248 to engage the next tooth on the ratchet wheel 241, whereupon the pawl and ratchet mechanism I21 is set for the next operation. Thus it will be understood that when the magnet Ml29 is repeatedly operated the operating element I 20 is repeatedly stepped in the clockwise direction, causing the fingers FI2I, etc. sequentially to select'the associated bell cranks LI2I etc., as previously explained.

Also, the upper bracket 241 supports a set of switch springs I operatively associated with an insulating button 252 carried by the armature 246, whereby the set of switch springs 25] is actuated each time the armature is operated; which arrangement may be utilized for the purpose of impulsing associated apparatus. Also, a set of off-normal switch springs 253 is associated with the operating element I 20 and, as best shown in Fig. 19, is provided with an operating element in the form of a collar 254 rigidly secured to the operating element I20. More particularly the collar 254 is formed of insulating material and has a notch 255 formed therein, into which the outer end of the innermost switch spring in the set 253 rides in order to open the associated contacts when the operating element I20 is rotated to its home position. 01 course it will be understood that when the operating element I 20 is rotated out of its home position the outer end of the innermost switch spring in the set 253 rides out of the notch 255 formed in th collar 254, whereby the contacts carried by the set of onnormal springs 253 are actuated into engagement. The rear ends of the individual springs in the set of oiT-normal springs 253 are securely clamped in place between insulating strips by an arrangement including a clamping plate 256 secured to the side plate 223 by a plurality of screws 251.

Further, an arrangement .is provided for centering the operating element I20 in any one of its stripped positions; which arrangement comprises, as best shown in Figs. 11 and 12, a leaf spring 258 secured to theside plate 223 by a clamping plate 259 and a plurality of screws 260. The leaf spring 258 carries a roller 26l adjacent to the outer end thereof that is pressed towardthe left, as viewed in Fig. 11, into engagement with a toothed wheel 262 rigidly secured to the operating element I20. More particularly, the roller 26! rides between two of the teeth provided on the wheel 262, thereby to center the operating element I20 accurately after it has been stepped by the associated rotary magnet MI29.

The lift magnet MI30 comprises, as best shown in Figs. 11 and 12, a heel piece 263, supporting a core 264 carrying a'winding 265, and an armature I32 pivotally mounted upon the heel piece 263. The outer end of the armature I32 is bifurcated to provide two arms 266 embracing the lower end of the operating element I20 and disposed above the lower bracket 242. The extreme outer ends of the arms 266 project upwardly and are rounded to cooperate with the lower surface of an adjacent collar 261 rigidly secured to the operating element I20. Further, the armature I 32 carries a rearwardly extending arm 268 supporting an insulator 269 cooperating with a set of switch springs 210 secured to the heel piece 263 by an arrangement including a clamping plate 21! and a plurality of screws 212. When the winding 265 is energized the core 264 attracts the armature I32, whereby it is rotated in the clockwise direction, as viewed in. Fig. 12, causing the arms 266 to engage the collar 261, thereby to slide longitudinally toward the top of the frame 220 the operating element I20. When the operating element I20 is thus moved longitudinally toward the top of the frame 220, the set finger FI2I, etc. engages the associated bell crank LI2I, etc. Also, when the armatur I32 is thus operated the insulator 269 operates the set of switch springs 210. Subsequently, when the winding 265 is .deenergized, the core 264 releases the armature I32, whereby it is returned to its home position by the action of gravity. Specifically, the armature I32 is rotated in the counterclockwise direction, as viewed in Fig. 12, back into its home position, whereupon operation thereof is arrested by a pin 213 carried by the side plate 223. Moreover, when the armature I32 is thus released the arms 266 permit the operating element I20 to be returned to its hom position by the action of gravity, the operating element I20 being slid longitudinally toward the bottom of the frame 220 in order to cause the finger FI2I, etc. engaging the associated bell crank LI2I, etc. to be moved into disengagement therewith, as previously noted. Finally, when the armature I32 is thus released, the insulator 269 carried b the arm 268 permits the set of switch springs 210 to be actuated back into its normal position. 

